Fuel injector control system and method

Abstract

A fuel injector for an engine is disclosed. The fuel injector has a plunger disposed within a bore, a nozzle member, a valve needle, a check valve, a spill valve, and a controller. The check valve is movable between a first position at which the valve needle is communicated with the bore, and a second position at which the valve needle is fluidly communicated with a drain. The spill valve is movable between a first position at which fuel flows from the bore to the drain, and a second position at which the fuel from the bore is blocked. The controller moves the spill valve toward its second position and the check valve toward its second position during a downward displacing movement of the plunger. The controller detects an unsuccessful movement of the check valve to the second position, and prematurely halts the current injection event in response to the detection.

What is claimed is: 
     
       1. A fuel injector, comprising:
 a plunger reciprocatingly disposed within a bore; 
 a nozzle member having a tip end with at least one orifice; 
 a valve needle having a base end and tip end, being disposed within the nozzle member, and movable against a spring bias from a flow blocking position at which substantially no fuel flows through the at least one orifice, to a flow passing position at which fuel flows through the at least one orifice; 
 a check valve in fluid communication with the bore and the base end of the valve needle, the check valve movable between a first position at which the base end of the valve needle is fluidly communicated with the bore, and a second position at which the base end of the valve needle is fluidly communicated with a drain; 
 a spill valve associated with the bore and movable between a first position at which fuel flows from the bore to the drain, and a second position at which the fuel from the bore is blocked from the drain; and 
 a controller in communication with the check valve and the spill valve, the controller being configured to:
 move the spill valve toward its second position during a downward displacing movement of the plunger to build pressure within the bore; 
 move the check valve toward its second position during the downward displacing movement of the plunger; 
 detect an unsuccessful movement of the check valve to the second position; and 
 prematurely halt a current injection event in response to the detection. 
 
 
     
     
       2. The fuel injector of  claim 1 , wherein the check valve is electronically controlled and the controller moves the check valve by directing current to the check valve. 
     
     
       3. The fuel injector of  claim 2 , wherein the controller detects an unsuccessful movement by comparing a current level through the check valve to a predetermined current range. 
     
     
       4. The fuel injector of  claim 3 , wherein the controller halts the current injection by returning the spill valve to its first position. 
     
     
       5. The fuel injector of  claim 4 , wherein the controller is configured to return the spill valve to its first position, if the current level through the check valve deviates from the predetermined current range. 
     
     
       6. The fuel injector of  claim 2 , wherein the spill valve is also electronically controlled and the controller moves the spill valve by directing a current to the spill valve. 
     
     
       7. The fuel injector of  claim 1 , wherein the controller is further configured to log a fault in a memory thereof each time the fuel injection event is prematurely halted. 
     
     
       8. The fuel injector of  claim 1 , wherein the controller is further configured to send a fault signal to an operator of an associated engine only after multiple faults have been logged. 
     
     
       9. The fuel injector of  claim 1 , wherein the plunger is mechanically cam driven to reciprocate. 
     
     
       10. A method of operating a fuel injector, comprising:
 displacing fuel; 
 blocking a flow of the displaced fuel to pressurize the displaced fuel; 
 directing the pressurized fuel to at least one orifice and to the base end of a valve needle blocking the at least one orifice; 
 attempting to lower the pressure of the fuel at the base end of the valve needle to allow the pressurized fuel to flow through the at least one orifice; 
 detecting an unsuccessful attempt to lower the pressure; and 
 prematurely unblocking the flow of displaced fuel in response to the detection. 
 
     
     
       11. The method of  claim 10 , wherein the steps of blocking and attempting both include generating an electronic command signal and directing the electronic command signal to a valve element. 
     
     
       12. The method of  claim 11 , wherein the step of detecting includes comparing the value of the electronic command signal received back from the valve element to a predetermined signal range. 
     
     
       13. The method of  claim 12 , wherein the step of prematurely unblocking includes is carried out if the comparison indicates that the electronic command signal received back from the valve element deviates from the predetermined signal range. 
     
     
       14. The method of  claim 10 , further including logging a fault each time the flow of displaced fuel is prematurely unblocked. 
     
     
       15. The method of  claim 14 , further including sending a fault signal to an operator of an associated engine only after multiple faults have been logged. 
     
     
       16. An internal combustion engine, comprising:
 an engine block having at least one combustion chamber; and 
 a fuel injector configured to selective inject fuel into the at least one combustion chamber, the fuel injector including:
 a plunger reciprocatingly disposed within a bore; 
 a cam mechanism operatively connected to reciprocatingly drive the plunger in the bore; 
 a nozzle member having a tip end with at least one orifice; 
 a valve needle having a base end and tip end, being disposed within the nozzle member, and movable against a spring bias from a flow blocking position at which substantially no fuel flows through the at least one orifice, to a flow passing position at which fuel flows through the at least one orifice; 
 a check valve in fluid communication with the bore and the base end of the valve needle, the check valve movable between a first position at which the base end of the valve needle is fluidly communicated with the bore, and a second position at which the base end of the valve needle is fluidly communicated with a drain; 
 a spill valve associated with the bore and movable between a first position at which fuel flows from the bore to the drain, and a second position at which the fuel from the bore is blocked from the drain; and 
 a controller in communication with the check valve and the spill valve, the controller being configured to:
 move the spill valve toward its second position during a downward displacing movement of the cam-driven plunger to build pressure within the bore; 
 move the check valve toward its second position during the downward displacing movement of the cam-driven plunger; 
 detecting an unsuccessful movement of the check valve to the second position; and 
 prematurely halt the current injection event in response to the detection. 
 
 
 
     
     
       17. The internal combustion engine of  claim 16 , wherein the check valve and the spill valve are both electronically controlled and the controller moves the check valve and the spill valve by directing currents to the check valve and the spill valve. 
     
     
       18. The internal combustion engine of  claim 17 , wherein:
 the controller detects an unsuccessful movement by comparing a current level through the check valve to a predetermined current range; 
 the controller halts the current injection by returning the spill valve to its first position; and 
 the controller returns the spill valve to its first position, if the current level through the check valve deviates from the predetermined current range. 
 
     
     
       19. The internal combustion engine of  claim 16 , wherein the controller is further configured to log a fault in a memory thereof each time the fuel injection event is prematurely halted. 
     
     
       20. The internal combustion engine of  claim 19 , wherein the controller is further configured to send a fault signal to an operator of an associated engine only after multiple faults have been logged.